Intake Air Filter for Internal Combustion Engines

ABSTRACT

The intake air filter according to the invention is for cleaning intake air for internal combustion engines, in particular in vehicles. To this end, the intake air filter comprises an openable housing ( 10 ) with an inlet ( 14 ) and an outlet ( 15 ). Disposed between the inlet ( 14 ) and the outlet ( 15 ) is an annular, closed main filter element ( 17 ) and an annular, closed secondary element ( 31 ). The secondary element ( 31 ) is connected to the outlet ( 15 ), whereby no contamination can pass through to the outlet ( 15 ) when the main filter element ( 17 ) is replaced. A centering device ( 29, 30, 40, 41, 42 ) is provided on the end face opposite the outlet ( 15 ) between the secondary element ( 31 ) and the main filter element ( 17 ), said centering device being used to fix the position of the secondary element ( 31 ) within the main filter element ( 17 ). This prevents relative movements between the main filter element ( 17 ) and the secondary element ( 31 ).

TECHNICAL FIELD

The present invention concerns an intake air filter for internalcombustion engines according to the preamble of claim 1.

PRIOR ART

EP 1 201 289 discloses an intake air filter that comprises a two-parthousing with a main filter element and a secondary filter element. Aninlet for air to be purified and an outlet for purified air are arrangedon the housing. The secondary filter element is connected at one endface to the outlet in such a way that, when exchanging the main filterelement or when the main filter element is missing, no contaminants canreach the outlet. On the other end face the secondary element issupported in axial direction on the main filter element. In thisconnection, radial relative movements between the main filter elementand the secondary filter element may occur. By means of these relativemovements the attachment on the outlet may become loosened or the filterelements may be damaged.

It is an object of the invention to prevent relative movements betweenthe main filter element and the secondary element.

This object is solved by the features of claim 1.

SUMMARY OF THE INVENTION

The intake air filter according to the present invention serves forpurifying air for internal combustion engines. Such intake air filterscan be used in connection with stationary or mobile machines, inparticular in vehicles. The intake air filter comprises a housing thatcan be opened and has an inlet for air to be purified and an outletthrough which the purified air can flow out of the intake air filter andpass into the internal combustion engine. In advantageous embodimentsthe housing is of a three-part or multi-part configuration in order tobe able to realize simple shapes. These parts can then be produced in asimple way, for example, by a plastic injection molding method. Theindividual parts of the housing can be connected to each other in adetachable or non-detachable way wherein at least one part is detachablyconnected to the other parts in order to be able to perform a filterelement exchange. Advantageous kinds of connections of the parts are,for example, screw connections, clip-on connections, weld connections oradhesive connections that can be produced in a simple and inexpensiveway.

Between the inlet and the outlet a main filter element of an annularclosed shape is arranged that can have any cross-sectional shape, forexample, can be of a circular ring shape or can be oval. Moreover, themain filter element may be cylindrical or conical. The main filterelement comprises a filter medium that is suitable for purifying air.Such filter media can be, for example, filter papers with cellulose,non-woven filters of synthetic fibers or other suitable materials,wherein the filter media are embodied of a single layer or multi-layerconfiguration, folded or wound. The main filter element has arrangeddownstream thereof in the flow direction a secondary element wherein thesecondary element is connected seal-tightly to the outlet. For thispurpose, the secondary element can be screwed to, clamped or snapped onthe outlet. On the end face of the secondary element that is oppositethe outlet a centering device is provided that, in radial direction,secures the position of the secondary element within the main element inthat it prevents radial movements. For this purpose, the centeringdevice can be, for example, embodied by noses on the outer circumferenceof the secondary element that in radial direction project outwardly andcorrespond with an appropriate counter contour on the innercircumference of the main filter element. Moreover, the centering devicein another embodiment can also be arranged centrally in the area of acomponent center axis.

Due to manufacturing tolerances or thermal expansions in axial directionlength differences of the secondary elements and main filter elementsmay result. For avoiding undesirable tensions in the longitudinaldirection, the centering device is provided in axial direction with alength compensation. Accordingly, on the one hand, radial movements thatcan cause uncontrolled detachment of the secondary element are preventedand, on the other hand, axial movements that can lead to tensions andimpairment of the filter elements are allowed.

According to an advantageous embodiment of the intake air filteraccording to the present invention, the main filter element comprises onthe end face that is opposite the outlet a fluid-tight bottom that, forexample, may be formed by polyurethane foam. Moreover, the bottom can becomprised of a shape-stable material, for example, sheet metal or aplastic disk, and can be connected by means of an adhesive seal-tightlyto the filter medium. Accordingly, additional sealing means forseparating the inlet from the outlet are not needed. On the bottom thecentering device is arranged. In this connection, a part of thecentering device can be integrally formed on the bottom or can beconnected detachably or non-detachably as a separate component with thebottom. Detachable connections can be generated, for example, byslipping on, clipping on or by screws. Non-detachable connectionsbetween the bottom and the centering device can be formed, for example,by adhesives or by fusing. The arrangement of the centering device onthe bottom provides that the secondary element has two bearing locationsspaced-apart from each other that optimally support the secondaryelement and thus prevent undesirable movements. Moreover, complexcontours for supporting the secondary element in the housing are notrequired.

In a further embodiment of the invention, the secondary element has, onits end face that is opposite the outlet, a fluid-tight cover on which apart of the centering device is arranged. This cover can be designed inaccordance with the afore described bottom of the main filter element.By the arrangement of the centering device on the cover, neighboringcomponents correspond with each other and enable simple geometrieswithin the housing.

It is advantageous that the main filter element comprises a support pipeof a shape-stable material, in particular, a thermoplastic syntheticmaterial. The support pipe has a plurality of air passages and generatestherefore no noteworthy pressure loss for the air flowing through. Sincethe support pipe is arranged on the outlet side of the filter medium, itis prevented that the filter medium is deformed by the air passingthrough. The fluid-tight bottom is advantageously formed integrally onthe support pipe so that the afore described function of the bottom isintegrated into the support pipe required for filter medium support. Asa result of the functional integration the number of components can bereduced. Also, additional connections between bottom, filter medium andsupport pipe are not needed.

A further embodiment of the invention provides that the secondaryelement has a support body which has the cover formed integrallythereon. The embodiments with regard to the support pipe of the mainfilter element apply in the same way also to the support body of thesecondary element.

According to an advantageous embodiment of the invention, the centeringdevice comprises a receiving device that is formed as a receiving crownwith webs arranged in distributed fashion. The webs of the receivingcrown will slightly move apart elastically when mounting the oppositemember and enable in this way a play-free support of the counter memberin the receiving crown.

In an alternative embodiment of the invention the centering devicecomprises an annularly shaped receiving wall as a receiving device. Thisreceiving wall is embodied as a rigid element. The corresponding countermember can be inserted into the receiving wall and be surrounded by itcircumferentially or can be pushed onto the receiving wall and surroundthe receiving wall.

According to another advantageous embodiment, the centering device hasan insertion device embodied as a pin which forms the counter member ofthe receiving device. In this connection, the pin can be embodied as arigid element and can be inserted into the above described receivingcrown. In other embodiments, the pin can also be comprised of elasticmaterial and can be embodied as a compressible element. In this way, aplay-free support of the secondary element in the filter element isenabled.

In a special embodiment on a rigid pin an elastic or compressible ringis arranged. This ring enables a simple installation because it iscompressed upon insertion of the pin into the receptacle. In this way,tolerances between the components can be compensated without play beinggenerated.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in the following with the aid ofembodiments in more detail. It is shown in:

FIG. 1 an intake air filter in section; and

FIG. 2 a detail of the intake air filter in an alternative embodiment.

EMBODIMENT(S) OF THE INVENTION

In FIG. 1, an intake air filter is illustrated in section. The intakeair filter comprises a housing 10 that can be opened and is comprised ofa thermoplastic synthetic material. In this embodiment the housing 10 iscomprised of a cover 11, a central part 12, and a cup 13. As a result ofthe multi-part configuration of the housing 11, the individual parts 11,12, 13 have a simpler geometry and can therefore be produced in a moresimple and less expensive way. The cover 11 is fused fixedly with thecentral part 12 thus forming a constructive unit. The cup 13 isdetachably connected to the central part 12 wherein for attachment ofthe parts 12, 13 to each other, for example, clamp clips (notillustrated) or the like can be used. The central part 12 has an inlet14 through which air to be purified flows into the housing 10. The cover11 comprises an outlet 15 that is integrally formed on the cover 11 soas to project in a socket shape outwardly. The inner contour of thecover 11 has a cylindrically extending sealing collar 16 onto which amain filter element 17 with a first end disk 18 arranged at its end faceis seal-tightly pushed. The end disk 18 is comprised of a compressiblepolyurethane foam that forms a sealing bead 19 and a disk area 20. Thesealing bead 19 corresponds in radial direction seal-tightly with thesealing collar 16. In axial direction the sealing bead 19 contacts theend face of the cover 11. Into the disk area 20 a folded filter medium21 of annularly closed shape projects and, at the end face, isseal-tightly embedded by foaming in the disk area 20. On the oppositeend face of the filter medium 21 a second end disk 22 of polyurethanefoam is arranged that also has a disk area 20 as described above. On thedisk area 20 a support bead 23 is integrally formed that may be embodiedin a circumferentially extending ring shape or divided into severalpartial segments. The support bead 23 is compressed axially within thehousing 10 so that axial play of the main filter element 17 in thehousing 10 is prevented. This support bead 23, when the cup 13 isclosed, projects into an annular receptacle 24 and reduces in this wayvibrations of the filter element 17 in the housing 10. In the interiorof the filter medium 21 a support pipe 25 is arranged which has aplurality of window-shaped passages 26. The support pipe 25 has at itsfirst end face a slotted end area 27 that is surrounded at the end faceby the disk area 20. Therefore, the main filter element 17 is providedwith a satisfactory radial elasticity in order to be pushed onto thesealing collar 16. On the opposite end face the support pipe 25 has aclosed slightly inwardly curved bottom 28. On the inwardly projectingside of the bottom 28 a cup-shaped receiving wall 29 is arranged. Intothis receiving wall 29 a pin 30 of a secondary element 31 that isarranged within the main filter element 17 projects. This secondaryelement 31 has a support body 32 that, like the support pipe 25 of themain filter element 17, has a plurality of rectangular passages 26. Thesupport body 32 has also a fluid-tight cover 33 on which the pin 30 isintegrally formed. On the pin 30 there is a compressible ring 34arranged that serves for vibration reduction between the secondaryelement 31 and the main filter element 17. Moreover, mounting of thecentering device, formed by the pin 30 and the receiving wall 29, isfacilitated by the ring 34. The height of the receiving wall 29 and thelength of the pin 30 are selected such that the main filter element 17contacts the sealing collar 16 before the pin 30 contacts the receivingwall 29. Only when the filter element 17 is being inserted farther, thepin 30 contacts the receiving wall 29. In order to facilitate mounting,either the pin 30 or the receiving wall 29 can have an insertion ramp(not illustrated). Mounting of the main filter element 17 is facilitatedin this way.

On the end face of the support body 32 opposite the pin 30 a fasteningthread 35 is arranged that is screwed into an appropriate counter thread36 on the housing. As a seal between this secondary element 31 and thecover 11, an O-ring 37 is provided that is supported on a surface of thecounter thread 36. The secondary element 31 comprises furthermore anon-woven filter 38 that covers the area of the passages 26 and in thearea of the end faces is attached by means of an adhesive 39 on thesupport body 32. As an alternative to the adhesive connection, thenon-woven filter 38 can also be fused seal-tightly with the support body32 or can be embedded by foaming, for example, with PUR foam. Moreover,the fastening means of the non-woven filter 38 on the two end faces maybe different. In this connection, any combination of fastening means ofthe different end faces are possible so that the non-woven filter 38 canbe fused, for example, to one end face and can be glued, for example, tothe other end face.

For purifying the intake air of the internal combustion engine theunfiltered air flows in the direction of the arrow into the inlet 14 andis distributed about the main filter element 17. Because of the pressureconditions that exist in the intake air filter, the air passes throughthe filter medium 21 and the particles contained in the air aredeposited on the filter medium. The purified air flows through thepassages 26 to the secondary element 31. In the purified air there areno further particles to be separated so that the air passes through thenon-woven filter 38 and the support body 32. From the inner volume ofthe secondary element 31 the air flows in direction of the arrow throughthe outlet 15 out of the intake air filter in the direction toward theinternal combustion engine.

When exchanging the main filter element 17, first the cup 13 isseparated from the central part 12. The main filter element 17 cansubsequently be pulled off by hand wherein the pin 30 is pulled out ofthe receiving wall 29 and the sealing bead 19 is removed from thesealing collar 16. The secondary element 31 remains screwed onto thecover 11 so that no contaminants can reach the outlet 15. Upon insertionof a new main filter element 17, the sealing bead 19 is pushed partiallyonto the sealing collar 16 before the pin 30 is immersed in thereceiving wall 29. After the main filter element 17 has been completelypushed onto the sealing collar 16 and the pin 30 is centered in thereceiving wall 29, the cup 13 can be connected again to the central part12.

In FIG. 2, a detail of the intake air filter in an alternativeembodiment is illustrated. Same components are identified with samereference characters. In contrast to FIG. 1, the support body 32 hassubstantially triangular passages 26′. Moreover, on the pin 30 of thesupport body no additional ring 34 is arranged. Moreover, the non-wovenfilter 38 is fused without additional components to the support body 32.The main filter element 17 comprises on its bottom 28 a receiving crown40 that is comprised of individual webs 41. These webs 41 moveelastically apart when subjected to a defined pressure and enable inthis way the reception of the pin 30. When doing so, the hard syntheticmaterial of the pin 30 glides along the webs 41 that are comprised alsoof a shape-stable synthetic material. To facilitate mounting, the pin 30has an insertion ramp 42 that, for example, is embodied as a bevel or arounded portion. The support pipe 25 of the main filter element 17 hasat the area near the end face guiding ribs 43 that effect a roughcentering action of the secondary element 31 in the main filter element17 and therefore facilitate installation. The pin 30 has in axialdirections sufficient play in the receiving crown 40 so that a lengthcompensation is achieved and therefore length tolerances or thermalexpansions will not damage the filter elements 17, 31.

Of course, the individual partial aspects of the different embodimentscan be combined in a suitable way with each other. Moreover, a reversalof the geometric arrangement of pin and receptacle is conceivable.

1.-10. (canceled)
 11. An Intake air filter filtering air flow into aninternal combustion engine, comprising: a housing enclosing a chambertherein, said housing openable to access said chamber, said housingincluding an airflow inlet; and an airflow outlet; a main filter elementarranged with said chamber, said filter element seal-tightly arrangedbetween the inlet and the outlet such that airflow flowing from saidinlet to said outlet is required to flow through said main filterelement, wherein said main filter element has an annularly closed shape,a secondary element having an annularly closed shape, said secondaryelement arranged downstream of said main filter element in flowdirection and connected seal-tightly with the outlet such that airflowfrom said chamber in said outlet is required to flow through saidsecondary element; a centering device arranged at an end face of saidmain filter element, said end face on an axial end of said main filterelement opposite said airflow outlet, wherein said centering device isoperable to fix radial position of said secondary element within saidmain filter element, wherein said centering device is provided betweensaid secondary element and said main filter element.
 12. The Intake airfilter according to claim 11, wherein the main filter element on anaxial end face opposite the airflow outlet comprises a fluid-tightbottom closing off an open interior of said main filter element at saidmain filter element axial end face, wherein a part of said centeringdevice is arranged on said fluid-tight bottom.
 13. The Intake air filteraccording to claim 11, wherein an axial end face of said secondaryelement positioned opposite said airflow outlet comprises a fluid-tightcover closing off an open interior of said secondary element at saidsecondary element axial end face; wherein a part of said centeringdevice is arranged on said fluid-tight cover.
 14. The Intake air filteraccording to claim 12, wherein said main filter element comprises asupport pipe having a plurality of airflow passages extending through awall of said support pipe, wherein said fluid-tight bottom is integrallyformed and unitary with said support pipe.
 15. The Intake air filteraccording to claim 13, wherein said secondary element comprises asupport body on which said fluid-tight cover is integrally formed andunitary with.
 16. The Intake air filter according to claim 11, whereinsaid centering device comprises a receiving device which is formed as areceiving crown with webs arranged in a distributed fashion.
 17. TheIntake air filter according to claim 11, wherein said centering deviceincludes a receiving device which is formed as an annular receivingwall.
 18. The Intake air filter according to claim 11, wherein saidcentering device comprises an insertion device that is embodied as apin.
 19. The Intake air filter according to claim 18, wherein acompressible ring is arranged on said pin.
 20. The Intake air filteraccording to claim 11, wherein said centering device in axial directionhas a length compensation.
 21. The Intake air filter according to claim12, wherein an axial end face of said secondary element positionedopposite said airflow outlet comprises a fluid-tight cover closing offan open interior of said secondary element at said secondary elementaxial end face, wherein a part of said centering device is arranged onsaid fluid-tight cover; wherein said main filter element comprises asupport pipe having a plurality of airflow passages extending through aa wall of said support pipe; wherein said fluid-tight bottom isintegrally formed and unitary with said support pipe, wherein saidcentering device includes an annularly arranged receiving devicearranged on said fluid tight bottom, wherein said centering devicecomprises an insertion device that is embodied as a pin, said pinintegrally formed on said fluid-tight cover, said pin having a portionreceived within said receiving device.
 22. The Intake air filteraccording to claim 21, wherein wherein a compressible ring is arrangedon said pin between said pin and said receiving device, saidcompressible ring abutting against said pin and said receiving device.